You may remember past agebuzz posts describing the emergence of blood tests that, in conjunction with clinical assessments, can be used to diagnose Alzheimer’s disease. Last spring, the FDA approved the Lumipulse blood test for adults aged 55 and older, who, when attending specialty clinics, could use the blood test to help confirm an Alzheimer’s diagnosis after experiencing symptoms of cognitive impairment. It appears that this test has not yet received insurance coverage. Still, given the high accuracy of the test and the costly and invasive alternative options for confirming the presence of Alzheimer’s (i.e., a spinal tap or PET scan), it’s likely that such a blood test will play an important role in the future diagnosis and treatment of Alzheimer’s. That’s now even more likely given the recent FDA approval of another blood biomarker test for Alzheimer’s. This additional new blood test, called Elecsys pTau 181, is intended for people aged 55 and older, with symptoms of cognitive decline, but this time, the test is permitted to be administered in a primary care office, rather than in a specialty neurologic clinic. This test rules out the presence of the pTau 181 protein, meaning that it is highly predictive in determining that a person does not have Alzheimer’s, though there certainly can be other causes and types of dementia that can lead to cognitive impairment. Again, this is not a test for those who do not have cognitive symptoms but rather a test for those already troubled by memory or other cognitive problems who are seeking a cause for their impairment. For those for whom the test results indicate the presence of pTau 181, they will then need further testing to confirm an Alzheimer’s diagnosis. There is also some concern that kidney dysfunction, even in a mild form, might affect the validity of these blood biomarker tests.

Neither of these blood test options actually diagnose Alzheimer’s nor predicts its course in the absence of existing symptoms. In fact, patients may still need a PET scan or spinal tap if they undergo one of these blood tests. Furthermore, they are not for use by, or available for, the “worried well.” So, if you are healthy and cognitively intact but worry about your risk of Alzheimer’s in the future, neither of these tests will give you the information you may desire. Yet, for many with symptoms, these tests offer benefits and even relief. For example, for people confused by what is happening and worried about their symptoms, these blood tests may bring a sense of calm and peace- even control- and give them a direction for what comes next and how their condition may be treated (remember, we now have medications that can slow down cognitive decline in Alzheimer’s patients, especially if used early in the process). While the available drugs for patients with Alzheimer’s are not without risks, early diagnosis and the initiation of these drugs do give patients and their families an element of control that was previously lacking for people with Alzheimer’s, and they allow for deep personal conversations about balancing risks and benefits and even infusing a sense of hope that was previously absent for such patients.

Will there ever come a time when a simple blood test will enable a patient to determine if they are at risk for Alzheimer’s, before cognitive symptoms begin? A newly published study by researchers at the University of Connecticut suggests that such a test may not be too far off in our future. According to these researchers, they have developed 2 rapid and affordable blood tests that detect the early markers of Alzheimer’s and that may one day be available for patients to quickly detect the presence of a variety of illnesses, including Alzheimer’s, in the privacy of their doctor’s offices, or even in their own homes. Given that we know that evidence of Alzheimer’s exists in the brain for years, even decades before the first symptoms appear, such a blood test would be a remarkable achievement. We are not there yet, but given the rapid advance of new technologies, it may not be too far into the future to find out that you have the presence of Alzheimer’s in your brain at the same time you find your cholesterol levels are a bit high. Stay tuned, as the future begins to unfold before our eyes.